Field of the Disclosure
The present application relates to a three-dimensional (3-D) image display device.
Description of the Related Art
A 3-D image display device is classified into a stereoscopic 3-D display device and an auto-stereoscopic 3-D display device.
The stereoscopic 3-D display device realizes a large 3-D visual effect using left and right parallax images. Such a stereoscopic 3-D display device is classified into a glasses-type stereoscopic display device and a glasses-free stereoscopic 3-D display device. The glasses-type stereoscopic 3-D display device displays left and right parallax images on one of a liquid crystal display panel and a projector with switching polarization directions in a time division system, and enables users to each wear polarizing glasses or liquid crystal shutter glasses, in order to visualize a 3-D image. The glasses-free stereoscopic 3-D display device generally includes an optical plate, a parallax barrier or others, which is installed onto the surface or at the front side of a liquid crystal display panel, and used to separate light axis of left and right parallax images from each other.
Recently, with commercialization and technical development of the 3-D image display device, a patterned retarder corresponding to an optical film, with optical modulation characteristics varying along patterns, is being often applied to the 3-D image display device.
FIG. 1 is a schematic diagram showing the configuration of a 3-D image display device according to the related art.
Referring to FIG. 1, a 3-D image display device of the related art includes a liquid crystal display panel 1, a polarizing plate 3, and a patterned retarder 5.
The liquid crystal display panel 1 includes a plurality of pixels which is arranged in a matrix shape configured with columns and rows. The polarizing plate 3 is attached to the front surface of the liquid crystal display panel 1. This polarizing plate 3 is used to polarize light applied from a backlight unit (not shown) through the liquid crystal display panel 1 into a fixed direction.
The patterned retarder 5 is attached onto the front surface of the polarizing plate 3. Also, the patterned retarder 5 includes first patterned retarders 5a and second patterned retarders 5b. The first patterned retarders 5a are arranged to correspond to odd-numbered row pixels of the liquid crystal display panel 1, and the second patterned retarders 5b are arranged to correspond to even-numbered row pixels of the liquid crystal display panel 1. Also, the first patterned retarder circularly polarizes light passing through the odd-numbered row pixels of the liquid crystal display panel 1 in one direction, and the second patterned retarder 5b circularly polarizes light passing through the even-numbered row pixels in an opposite direction. The left-circularly polarized light and the right-circularly polarized light by the patterned retarder 5 are transferred to polarizing glasses 7 worn by a user.
The polarizing glasses 7 are used to separate an image into a left eye image and a right eye image.
Such polarizing glasses 7 include a left side glass 7a and a right side glass 7b. For example, the left side glass 7a transmits the image which is displayed on the odd-numbered row pixels and circularly polarized by the first patterned retarders 5a. According to this example, the right side glass 7b transmits the image which is displayed on the even-numbered row pixels and circularly polarized by the second patterned retarder 5b. 
In other words, different images are transmitted on the left side glass 7a and the right side glass 7b. As such, the user can view a 3-D image.
FIG. 2 is a side view showing a liquid crystal display panel and a patterned retarder according to the related art.
As shown in FIG. 2, the related art liquid crystal display panel 1 is defined into left eye regions L, right eye regions R, and black matrix regions B.
The left eye regions L can be arranged opposite to the first patterned retarders 5a, and the right eye regions R can be arranged opposite to the second patterned retarders 5b. The first patterned retarder 5a circularly polarizes light passing through the left eye region L, and the second patterned retarder 5b circularly polarizes light passing through the right eye region R.
The black matrix regions B do not transmit light and can be formed between the left eye regions L and the right eye regions R of the liquid crystal display panel 1. As the areas of the left eye region L and the right eye region R are reduced, the areas of the black matrix regions B are increased. Also, a viewing angle of the 3-D image display device being defined as a sum of a first viewing angle θ1 and a second viewing angle θ2 can increase.
As illustrated in FIG. 2, the first viewing angle θ1 (for example, a downward viewing angle) is defined as an angle between a perpendicular line to the liquid crystal display panel 1 and the patterned retarder 5 and a diagonal line connecting one end of the left eye region L and one end of the first patterned retarder 5a. Similarly, the second viewing angle θ2 (for example, an upward viewing angle) can be defined as another angle between the above-mentioned perpendicular line and another diagonal line connecting the other end of the left eye region L and the other end of the first patterned retarder 5a. 
However, the black matrix regions B included in the liquid crystal display panel 1 take up space and reduce an aperture ratio of the pixel. Due to this, less light is transmitted and brightness of the liquid crystal display panel 1 decreases.
Moreover, the left and right eye regions L and R and the first and second patterned retarders 5a and 5b are formed to each have a small pitch (or a small vertical height). Thus, misalignment of the liquid crystal display panel 1 and the patterned retarder 5 can cause an imaging problem. If misalignment occurs, the first viewing angle and the second viewing angle must be different from each other resulting in a viewing problem.